Such measuring heads are, for example, to be used to calibrate torque wrenches. The sensor means, conventionally, have strain gages. These strain gages are cemented to parts which are deformed by the torque to be measured. Such strain gages provide weak, analog signals. Usually, these analog signals are not exactly proportional to the torque exerted on the torque sensor. Therefore, signal processing is necessary to obtain a signal which exactly represents the torque. This signal is displayed by display means or is otherwise supplied to evaluation means, for example, for determining the variation in time or the statistical distribution of the torques.
Each torque sensor has a limited measuring range, in which it operates optimally. Therefore, different measuring heads with correspondingly different torque sensors are provided. These different measuring heads are connected to the display or evaluation means or are applied thereto through a selector switch.
Usually, the signal processing for generating a signal which exactly represents the torque is effected in the evaluation means. This seems to be reasonable, in particular if a plurality of torque sensors can optionally be connected to the display or evaluation means. Then, the signal processing means need be provided only once.
The transmitting of the analog signal to the display or evaluation means involves the risk of the signal being falsified by interferences. Expensive shielding measures are required.
Connecting or switching measuring heads to the display or evaluation means is complex and may result in operating errors.